Epigenetic Memory of Plant Stress Response The ability to acquire information from a novel environment and present a defined change in behavior defines learning and memory. Although sessile, plants, nonetheless, respond to novel environmental conditions with alterations in gene expression and developmental phenotypes to improve fitness in a changing environment (Arnholdt-Schmitt, 2004). However, the mechanistic basis of plant memory of a stressful environment remains to be fully understood. Studies in Aplysia and in mammals have revealed a conservation of cellular mechanisms contributing to the biology of learning (Levenson and Sweatt, 2006). For example, the basis of memory formation lies with neuronal plasticity, wherein biochemical and structural changes, mediated through epigenetic control, facilitate adaptation. While many of the pathways utilized by animals during cognitive memory formation, such as calcium-dependent signaling and expression of early-response genes are similarly activated during plant stress reflex, the role of chromatin remodeling in plant stress response remains uninvestigated. As the main objective, this proposal strives to investigate the role of epigenetic regulation of chromatin structure, as a dynamic and sustainable paradigm utilized by plants to encode environmental stress, with two major aims using the model system Arabidopsis thaliana. Aim 1 will determine whether memory of abiotic stress exists in Arabidopsis, as evidenced through epigenetic regulation of gene expression. Aim 2 will investigate the epigenetic mechanisms in mediating learning and memory of abiotic stress in Arabidopsis. This will include the analysis of mutants in chromatin modifying genes and the identification of novel down-stream targets in plant epigenetic memory of stress response, using candidate selection and ChlP-CHIP screenapproaches. Health relevance: Investigation of epigenetic mechanisms of environmental stress memory in plants holds significant bearing in addressing the universal need for the maintenance of sustainable food crops despite a constantly changing global climate. Additionally, emerging discoveries of disruptions in molecular components of chromatin remodeling machinery resulting in human neurological disorders provide a testament to the crucial role of epigenetic mechanisms in development and human cognitive function. Sharing the fundamental eukaryotic attributes of epigenetic mechanisms, Arabidopsis represents an appealing model system, providing an alternative insight to how organismsform memory to store information about their surroundings